We have one Rosendahl make Extruder of size 30 mm.
The Extruder is supplied with two self Centering cross heads i.e. SF3 & SF10, which are supplied by M/S. SWISSCAB. We are extruding ETFE (Tefzel HT
2185) manufactured by M/S. Du Pont and ECTFE (Halar 500 LC) manufactured by M/S. Solvay but we are unable to get proper centre of the core.though we are
using self centred cross heads. Due to which we are not able to maintain proper thickness of insulation.
As you no doubt know, Rosendahl is an excellent manufacturer of extruders and Swisscab is an excellent manufacturer of crossheads and extrusion tooling.
There are only three basic reasons why you are having eccentricity problems with your wire. One is that you have too much clearance between the core and the tip for whatever the reason. The second is that the crossheads have lost their accuracy by wear and need to be rebuilt, preferably by Swisscab. The third is that the tooling is inaccurate by wear or manufacture and needs to be replaced.